U.S. immigration authorities’ lack of progress in automating their systems is compromising border security, making it more difficult to process people seeking to get into the country, a report said on Tuesday.

“We may be admitting individuals who wish to do us harm, or who do not meet the requirements for a visa,” John Roth, the Inspector General for the Department of Homeland Security, told a Senate Homeland Security Committee hearing.

The report from Roth’s office, released on Tuesday, said immigration officials expect it will take $1 billion and another three years, 11 years into the effort, to move from a paper-based system to automated benefit processing.

U.S. lawmakers have been calling for a tighter visa system since the November Paris attacks and December San Bernardino shootings. In Paris, some of the militants were Europeans radicalized after visiting Syria, and a California attacker had been admitted on a fiance visa.